1. Technical Field
The present invention relates to a radiation detector.
2. Related Art
Radiation detectors are recently being applied with Flat Panel Detectors (FPD) disposed with a radiation sensitive layer over a Thin Film Transistors (TFT) active matrix board and capable of converting radiation directly into digital data. Such radiation detectors have the advantage of enabling immediate image and video image checking to be performed. Radiation detectors are available with various types of radiation conversion, such as an intermediate conversion type in which radiation is first converted into light by a scintillator and then converted into accumulated charge by a semiconductor layer such as a photodiode, and a direct conversion type in which radiation is directly converted into charge by a semiconductor layer such as of amorphous selenium. Various types of material may be employed in the semiconductor layers for both types of radiation detector.
Radiographic imaging apparatuses (referred to below as electronic cassettes) installed with such radiation detectors are being put into practice to store radiographic imaging data output from the radiation detectors.
Due to their portability such electronic cassettes can be flexibly utilized on immobile patients since imaging can be accomplished with a patient still lying on a stretcher or bed, and such electronic cassettes enable the imaging location to be adjusted simply by changing the position of the electronic cassette.
Examples of radiation detectors installed in electronic cassettes include radiation detectors with a support body for vacuum depositing a radiation sensitive layer (referred to below as a scintillator layer) on, the scintillator layer for converting input radiation to light, and a TFT active matrix board (referred to below as a photo detector plate) for converting light emitted by the scintillator layer into charge attached to the scintillator layer.
A sealing layer is needed between the support and the photo detector plate to prevent moisture penetration to the side faces of the scintillator layer when the scintillator layer is configured by a deliquescent material, as described in Japanese Patent Application Laid-Open (JP-A) No. 2002-148343.
However, in JP-A No. 2002-148343, the linear expansion coefficients (thermal expansion rates) of the photo detector plate and the support body differ from each other due to the photo detector plate configuring the radiation detector being formed from glass, and the support body being configured from glass and aluminum. The photo detector plate and the support body hence warp towards the outside face directions due to thermal expansion occurring with fluctuations in the internal temperature of the electronic cassette. Warping of the support body is particularly significant when the whole of the support body is configured from aluminum, although this aspect is not referred to in JP-A No. 2002-148343.
An issue hence arises of the sealing layer separating with an accompanying deterioration in moisture penetration prevention ability unless the sealing layer is able to conform to such warping.
While also not referred to in JP-A No. 2002-148343, sometimes the support body is covered in a protective layer in order to prevent corrosion by the material configuring the scintillator layer of a support body formed from a material such as aluminum. An issue arises in such cases of separation between the sealing layer and the support body protective layer it is adhered to due to warping of the support body and accompanying deterioration in moisture penetration prevention ability.